Is it possible in blender to change the dimensions of a downloaded 3d model in .blend format or .obj format in blender using python scripting?
I will be waiting for the clarification of the question and will do my best to edit my answer accordingly because the question is really poorly formed, however if you need a way to generate different human characters quickly defining properties and measurements of their body parts, you will definitely find ManuelBastioniLAB add-on interesting. It is a free and very well designed tool for parametric human character modeling.